"What are these?" Tetsu asked, turning away from her paintings to see the books Shin found.
They were bound in leather, some of it too smooth and light to belong to a cow or a pig. Some of them were in Japanese, but others were in English, Latin and languages Shin could only guess at. Aramaic?
He opened a book in Japanese and leafed through thick yellow pages. They made his fingertips tingle.
"Don't you recognize those, Tetsu? Or do you not remember yet?" Shin glanced at the demoness questioningly.
She hummed thoughtfully, and her lower lip jutted into a slight pout. The expression put emphasis on its fullness and the way the red skin looked smooth and juicy, like a sweet apple. It made saliva pool in Shin's mouth.
Tetsu caught Shin's staring—he felt her eyeless gaze—and smirked mischievously.
Shin startled and forcefully looked away, showing his emotions somewhere far, far away.
"I remember some of it, my friend. Those are books of magic," Tetsu said, moving closer to peer over Shin's shoulder. Instead of phasing through or into his body, she pressed her chest to his back. "Humans have so many languages and they change so quickly, that I'm not sure how many of them are still written with. And… My memory isn't as good as it was, not yet. But it will be, it will."
Shin nodded. "For now, what I know is enough. I wonder if I can make something useful out of this right now, while you eat the paintings."
"Got it, boss!" Tetsu said cheerfully and went to the paintings.
She took the nearest one, sighed with regret, and plunged her claws into it. They tore canvas and pulled out tiny, ghostly figures that the demoness crunched like potato chips.
Energy shot through her body, and Shin shivered from the echo of the sensation. He gripped the book tighter and kept reading it.
Since there were monsters, demons and deities in this world, of course, there would be magic. It wasn't anything like gathering mana and using techniques, though.
It was about making formations, writing talismans, and summoning demons. In fact, magic WAS demons. The same as them, at least.
If someone wrote special words and imbued them with powers of life and pain, they would become a new demon. Demons of the demon world were mostly written into life by gods or by each other. Humans normally didn't have that kind of power.
But humans could still write. Then they could create smaller demons, made for a specific purpose, obedient and barely sentient—spells.
Shin knew all about the basics and mechanics of using magic, he only needed to know the right words. Tetsu would've known them if she remembered, but for now, Shin could learn by himself.
The banging on the door was distracting, but Shin was getting used to it. The sensations from Tetsu devouring painting after painting, consuming dozens of souls at once, were much harder to shrug off.
He felt heady, almost drunk on that sudden rush of power. The room felt hot, and Shin's grip on the book turned tight enough to crumble pages.
"I ate them all, my friend. Except for one. But I can have one, right? It's just one…" Tetsu whispered in Shin's ear.
He jolted, turning around so quickly that his forehead almost smashed into her headpiece. The demoness grinned at him and licked her lips.
Shin swallowed. His eyes fell to Tetsu's chest and paused, widening.
"A new Verse!" Smiling, Shin reached out to touch the large red jewel that appeared in the center of Tetsu's metal-covered chest, then took the painting out of her arms and put it to his books. "That's great. Yes, give me that painting, I will keep it for now. Exactly three Verses. You must've remembered more of your abilities, too, Tetsu."
Her grin turned wider and hungrier.
"Yes. An ability with which we will destroy that annoying creature that tried to harm us," she said, glancing towards the exit from the vault. In a dreamy voice, Tetsu added, "Together. Really, really together."
Shin immediately understood what the demoness meant.
"So you can merge with me now?" The prospect was scary, but exciting. "That's—"
A faraway sound of a fire alarm came from somewhere. Shin's eyes widened.
"A fire alarm?"
He looked around, suddenly realizing that maybe the heat in the room wasn't just from Tetsu. The demoness looked around as well, then sniffed.
"I smell smoke, my friend. Is something burning?"
Shin clenched his fists. That wasn't supposed to happen! The plot of the story was derailed too far for it. Or was Mihara captured? Or—
With a sinking feeling, Shin remembered the conversation before. Mihara called the cultist leader by his secret name, which he wasn't supposed to know. Shin didn't tell him.
Could Mihara have remembered the plot, after all?
Was that related to the smell of smoke from outside?
Shin gave one last glance at the vault's contents. There were other items beyond the books and the torn paintings, but they weren't worth bothering. He picked up a small box of books and turned to Tetsu.
"Merge with me, Tetsu," Shin ordered. "We have much less time than we thought."
"All my strength is yours, my friend."
With those words, she stepped into his body. But unlike normal, when Tetsu simply nestled inside like a weight on the back of Shin's mind, this time she filled him in.
Her essence poured into Shin's body, changing it. Bones shifted with disgusting wet noises, skin changed color and texture, muscles tore and twisted. It was akin to a thousand fingers probing Shin all over from the inside—yet absolutely painless.
A few agonizingly long seconds later, it was all over.
Demonic might, unlike anything before, was going through their body. And that body was also unlike anything before.